1 2 #include <../src/mat/impls/baij/seq/baij.h> 3 #include <../src/mat/impls/sbaij/seq/sbaij.h> 4 5 /* 6 This function is used before applying a 7 symmetric reordering to matrix A that is 8 in SBAIJ format. 9 10 The permutation is assumed to be symmetric, i.e., 11 P = P^T (= inv(P)), 12 so the permuted matrix P*A*inv(P)=P*A*P^T is ensured to be symmetric. 13 - a wrong assumption! This code needs rework! -- Hong 14 15 The function is modified from sro.f of YSMP. The description from YSMP: 16 C THE NONZERO ENTRIES OF THE MATRIX M ARE ASSUMED TO BE STORED 17 C SYMMETRICALLY IN (IA,JA,A) FORMAT (I.E., NOT BOTH M(I,J) AND M(J,I) 18 C ARE STORED IF I NE J). 19 C 20 C SRO DOES NOT REARRANGE THE ORDER OF THE ROWS, BUT DOES MOVE 21 C NONZEROES FROM ONE ROW TO ANOTHER TO ENSURE THAT IF M(I,J) WILL BE 22 C IN THE UPPER TRIANGLE OF M WITH RESPECT TO THE NEW ORDERING, THEN 23 C M(I,J) IS STORED IN ROW I (AND THUS M(J,I) IS NOT STORED); WHEREAS 24 C IF M(I,J) WILL BE IN THE STRICT LOWER TRIANGLE OF M, THEN M(J,I) IS 25 C STORED IN ROW J (AND THUS M(I,J) IS NOT STORED). 26 27 -- output: new index set (inew, jnew) for A and a map a2anew that maps 28 values a to anew, such that all 29 nonzero A_(perm(i),iperm(k)) will be stored in the upper triangle. 30 Note: matrix A is not permuted by this function! 31 */ 32 PetscErrorCode MatReorderingSeqSBAIJ(Mat A, IS perm) 33 { 34 Mat_SeqSBAIJ *a = (Mat_SeqSBAIJ *)A->data; 35 const PetscInt mbs = a->mbs; 36 37 PetscFunctionBegin; 38 if (!mbs) PetscFunctionReturn(PETSC_SUCCESS); 39 SETERRQ(PETSC_COMM_SELF, PETSC_ERR_SUP, "Matrix reordering is not supported for sbaij matrix. Use aij format"); 40 #if 0 41 const PetscInt *rip,*riip; 42 PetscInt *ai,*aj,*r; 43 PetscInt *nzr,nz,jmin,jmax,j,k,ajk,i; 44 IS iperm; /* inverse of perm */ 45 PetscCall(ISGetIndices(perm,&rip)); 46 47 PetscCall(ISInvertPermutation(perm,PETSC_DECIDE,&iperm)); 48 PetscCall(ISGetIndices(iperm,&riip)); 49 50 for (i=0; i<mbs; i++) { 51 PetscCheck(rip[i] == riip[i],PETSC_COMM_SELF,PETSC_ERR_ARG_INCOMP,"Non-symmetric permutation, use symmetric permutation for symmetric matrices"); 52 } 53 PetscCall(ISRestoreIndices(iperm,&riip)); 54 PetscCall(ISDestroy(&iperm)); 55 56 if (!a->inew) { 57 PetscCall(PetscMalloc2(mbs+1,&ai, 2*a->i[mbs],&aj)); 58 } else { 59 ai = a->inew; aj = a->jnew; 60 } 61 PetscCall(PetscArraycpy(ai,a->i,mbs+1)); 62 PetscCall(PetscArraycpy(aj,a->j,a->i[mbs])); 63 64 /* 65 Phase 1: Find row index r in which to store each nonzero. 66 Initialize count of nonzeros to be stored in each row (nzr). 67 At the end of this phase, a nonzero a(*,*)=a(r(),aj()) 68 s.t. a(perm(r),perm(aj)) will fall into upper triangle part. 69 */ 70 71 PetscCall(PetscMalloc1(mbs,&nzr)); 72 PetscCall(PetscMalloc1(ai[mbs],&r)); 73 for (i=0; i<mbs; i++) nzr[i] = 0; 74 for (i=0; i<ai[mbs]; i++) r[i] = 0; 75 76 /* for each nonzero element */ 77 for (i=0; i<mbs; i++) { 78 nz = ai[i+1] - ai[i]; 79 j = ai[i]; 80 /* printf("nz = %d, j=%d\n",nz,j); */ 81 while (nz--) { 82 /* --- find row (=r[j]) and column (=aj[j]) in which to store a[j] ...*/ 83 k = aj[j]; /* col. index */ 84 /* printf("nz = %d, k=%d\n", nz,k); */ 85 /* for entry that will be permuted into lower triangle, swap row and col. index */ 86 if (rip[k] < rip[i]) aj[j] = i; 87 else k = i; 88 89 r[j] = k; j++; 90 nzr[k]++; /* increment count of nonzeros in that row */ 91 } 92 } 93 94 /* Phase 2: Find new ai and permutation to apply to (aj,a). 95 Determine pointers (r) to delimit rows in permuted (aj,a). 96 Note: r is different from r used in phase 1. 97 At the end of this phase, (aj[j],a[j]) will be stored in 98 (aj[r(j)],a[r(j)]). 99 */ 100 for (i=0; i<mbs; i++) { 101 ai[i+1] = ai[i] + nzr[i]; 102 nzr[i] = ai[i+1]; 103 } 104 105 /* determine where each (aj[j], a[j]) is stored in new (aj,a) 106 for each nonzero element (in reverse order) */ 107 jmin = ai[0]; jmax = ai[mbs]; 108 nz = jmax - jmin; 109 j = jmax-1; 110 while (nz--) { 111 i = r[j]; /* row value */ 112 if (aj[j] == i) r[j] = ai[i]; /* put diagonal nonzero at beginning of row */ 113 else { /* put off-diagonal nonzero in last unused location in row */ 114 nzr[i]--; r[j] = nzr[i]; 115 } 116 j--; 117 } 118 119 a->a2anew = aj + ai[mbs]; 120 PetscCall(PetscArraycpy(a->a2anew,r,ai[mbs])); 121 122 /* Phase 3: permute (aj,a) to upper triangular form (wrt new ordering) */ 123 for (j=jmin; j<jmax; j++) { 124 while (r[j] != j) { 125 k = r[j]; r[j] = r[k]; r[k] = k; 126 ajk = aj[k]; aj[k] = aj[j]; aj[j] = ajk; 127 /* ak = aa[k]; aa[k] = aa[j]; aa[j] = ak; */ 128 } 129 } 130 PetscCall(ISRestoreIndices(perm,&rip)); 131 132 a->inew = ai; 133 a->jnew = aj; 134 135 PetscCall(ISDestroy(&a->row)); 136 PetscCall(ISDestroy(&a->icol)); 137 PetscCall(PetscObjectReference((PetscObject)perm)); 138 PetscCall(ISDestroy(&a->row)); 139 a->row = perm; 140 PetscCall(PetscObjectReference((PetscObject)perm)); 141 PetscCall(ISDestroy(&a->icol)); 142 a->icol = perm; 143 144 PetscCall(PetscFree(nzr)); 145 PetscCall(PetscFree(r)); 146 PetscFunctionReturn(PETSC_SUCCESS); 147 #endif 148 } 149